Pruning Young Trees
Pruning correctly is crucial in the development of a young tree. With correct pruning you can achieve an attractive shape and a strong, sound structure. If you look after your tree its its early stages it will require little or no corrective pruning as it matures. Bear these points in mind before pruning a tree:
Before making a cut consider its purpose. Every cut has the potential to change the shape of the tree in the future. Bad pruning can damage the tree that lasts for rest of its life.
Learn where and how to make cuts before starting work. After a tree is wounded, it must grow over any damage. Because of this the wound is contained within the tree for the rest of its life.
Small cuts will do less damage to the tree than large cuts. For this reason it is preferable to prune trees when they are smaller as opposed to when they are mature and larger corrective cuts must be made.
Making the Cut
Placement of pruning cuts are vital to a tree’s growth and wound closure. Pruning cuts should be made just outside the branch collar to avoid damaging the trunk and to allow the cut to heal properly. Poor pruning cuts can lead to permanent damage and unseen internal decay. When a larger branch must be shortened, it should be pruned back to a secondary branch or a bud. When cuts made inappropriately between buds or branches they may lead to stem decay and misdirected growth.
Smaller branches can be pruned with hand tools, often by the owner. Secateurs can be used for smaller cuts but cuts larger than half an inch in diameter should be made with larger pruning shears or a pruning saw. Whatever tools you use, make sure they are sharp and make clean cuts.
Creating a Strong Structure For Your Tree
Creating a good structure of primary branches should be done when the tree is young. These early limbs are called scaffold branches and will create the framework for the tree as it matures. A young tree that is properly trained will develop a strong and solid structure that will need little corrective pruning as it matures. The aim in training young trees is to create a single, strong, central trunk with evenly spaced branches. Some trees will naturally develop these qualities, whilst others may require more regular maintenance.
Pruning and Trunk Development
When pruning most young trees it is preferable to maintain a single dominant leader growing upward. Avoid pruning the tip of this leader and allowing secondary branches to dominate the main leader. Some trees can naturally develop double leaders. These are called codominant stems. This situation can lead to structural weaknesses. The way to avoid this is to remove one of the stems when the tree is still young. When many branches are being removed, it is desirable to keep some, to promote trunk diameter growth. A trees secondary branches are important to a solid and well tapered trunk.
Selecting Permanent Branches
Many of the branches on a young tree will be pruned away at maturity to provide clearance for people and vehicles. The trees intended function will determine the height of the lowest branch. The crown of a street tree may be raised to five meters to allow traffic to pass safely. In most situations two or three meters is sufficient. If intending to you a tree as a screen or a windbreak it is likley that all lower branched would be retained. Having sufficient branch spacing and balance is important for a trees health and longevity. The ideal space between permanent branches should be around three percent of the tree’s mature height. It is important to maintain relative branch size when pruning. A branch that is of a similar diameter to its parent branch is more likely to fail than one that is smaller than its parent branch. Make sure one scaffold branch is not allowed to grow directly above another or allowed to cross eventually resulting in touching branches when the tree is mature. It is important not to remove too many branches when pruning. Photosynthesis occurs in leaves. Leaves and their supporting branches are important sites of food production and storage. Pruning back too much foliage and branches can starve the tree and retard growth. No more than one third of the crown should be removed in one season.
Newly Planted Trees
Pruning of freshly planted trees in their first year should only be the removal of dead or broken branches. Any other pruning should be wait until the tree has had a chance to establish in its new situation. The second or third year is appropriate for other work, when a tree has recovered from the stress of being moved.
Dressing wounds is now an old fashioned concept and research has now shown that wound dressings do not reduce decay or aid the closure of a wound. Most arborists will recommend that wound dressings should not be used.